1. Field of the Invention
The present invention relates to a communication apparatus capable of concurrently executing multiple communications through a plurality of channels.
2. Description of the Related Art
A group 4 facsimile connected to an ISDN, for example, is known as a facsimile apparatus having a plurality of channels.
In such a G4 facsimile, the multichannels of ISDN may be used to place a phone call from a telephone set belonging to the apparatus, while in its state of Group 4 facsimile transmitting to one destination to a different destination, or, during a transmission, to receive from a facsimile which is not involved in such transmission. It is also possible to perform a concurrent operation in which, during a transmission, another transmitting operation to a different destination is effected.
In general, there are two types of image transmitting methods in a conventional facsimile, i.e., memory transmission and direct transmission.
In the memory transmission method, data of the document to be transmitted is previously stored into a data accumulating memory and, after initiating the communication, the accumulated data is converted by a data conversion section correspondingly to the resolution and paper size of the receiver and the converted data is transmitted to the called facsimile apparatus.
In the direct transmission method, on the other hand, the facsimile at a destination is called before reading the document and, after ascertaining the possible paper size and resolution which may be received at the receiver, the reading operation is started to transmit the data to the receiver.
FIGS. 2A and 2B are flowcharts schematically showing each communication operation according to the above conventional two methods. FIG. 2A shows the flow of the image data in memory transmission while FIG. 2B shows flow of the image data in direct transmission.
Referring to FIG. 2A, data from a data accumulating memory is converted through a data conversion section. After being accumulated again into a data accumulating memory, the data is delivered to a data communication section so that the data is transmitted onto a line.
Since, in FIG. 2B, the resolution and document size are known when reading the document at a data input section such as a scanner, data is delivered to the data accumulating memory from the data input section and the data is then delivered to the data communication section to be transmitted onto a line.
In other words, while, in the direct transmission, the data input section such as a scanner is occupied during a transmission, what is occupied in the memory transmission is the data conversion section.
In a facsimile having a plurality of communication channels, a data conversion section corresponding to two separate transmitting operations is necessary if, during a memory transmission through one of the channels, a memory transmission through another channel is to be enabled. This results in higher cost.